In a vehicle which travels using an engine as a driving source, an engine control device for controlling a startup of the engine is included.
The engine control device controls a starter system driving a starter motor to perform a cranking control of the engine when the starter switch is operated by a user.
As the starter switch is operated by a user and the starting switch is turned on, the starter system controls a drive lever of a plunger to engage a pinion gear provided in an output shaft of the starter motor with a ring gear provided in an output shaft of the engine and to rotationally control the starter motor. In this way, the starter motor can be driven.
The drive lever can be controlled in such a way that a starter switch is operated by a user to cause the starting switch to turn on, an electric current is caused to flow from a battery mounted on the vehicle to a coil and an electromagnet opposed to the coil is magnetized. In this way, a magnetized electromagnet can move the drive lever in a direction opposite to the direction of an output shaft of the starter motor.
The pinion gear provided on the output shaft of the starter motor is connected to the drive lever. And thus, as the drive lever is controlled, the pinion gear moves in the direction opposite to the direction of the output shaft of the starter motor to engage with the ring gear provided in the output shaft of the engine which is located in a position opposite to the starter motor.
An abnormal noise can be occurred when the ring gear and the pinion gear are engaged with each other. The abnormal noise can be decreased when the teeth of each gear are smoothly engaged with the valleys of each gear, whereas the abnormal noise can be increased when the teeth of each gear are harshly engaged with the valleys of each gear. In order to suppress the abnormal noise, it is necessary to smoothly engage the teeth of each gear with the valleys of each gear. That is, it is necessary to engage the teeth of each gear with the valleys of each gear in a static state.
For example, in Patent Document 1, there is disclosed a technology which is capable of suppressing occurrence of the abnormal noise by driving the starter motor in a state where the gears are engaged with each other. Specifically, since the starter motor is driven after the electric current flows to the coil and then the gears are engaged with each other, the gears can be engaged with each other at timing when the gears are not rotated. Accordingly, it is possible to suppress the occurrence of the abnormal noise.
It is preferable that such a control is realized not by a software control including operating means such as a CPU, but by a hardware control such as a logic circuit which has no operating means such as a CPU and has a lower failure rate as compared to the software control. The reason is that since a faculty startup of the engine is a most important factor which significantly degrades the commodity value as compared to other malfunctions, it is extremely required that such a faculty startup of the engine is suppressed.
Meanwhile, as an example of a startup control of the engine, a startup control using an idling stop function can be exemplified. In the startup control using the idling stop function, in a time interval from a timing when a user operates a starter switch to turn on a starting switch, thereby turning on the engine to a timing when a user operates an ignition switch to an off state, thereby turning off the engine, the engine is stopped when a condition such as a stop of the vehicle is satisfied and the engine is started when a condition such as an acceleration operation by a user is satisfied.
Basically, in the startup control using the idling stop function, the engine is stopped when the vehicle is temporarily stopped and the engine is started when the vehicle departs. Accordingly, there is a trend that the startup control is frequently occurred.
In the startup control using the idling stop function, although it is necessary to rapidly start up the engine for improving user's convenience, the coil and the electromagnet which drive the drive lever of the starter system have a physical property that it is more difficult to generate a magnetic power for driving the drive lever in the electromagnet as an ambient temperature thereof becomes lower. Accordingly, in a case where the ambient temperature of the coil and the electromagnet is low, it is required to lengthen a time interval (delay time) from a timing when electricity flows to the coil to cause the gears to be engaged to a timing when the starter motor is controlled to be driven, as compared to a case where the ambient temperature is high.
In order to realize the startup control by the hardware control, a time capable of assuring a minimum actuating time of the plunger should be set as the delay time because it is not possible to suitably change the delay time according to the ambient temperature of the coil or the electromagnet. That is, a delay time in a case that a temperature of the coil or the electromagnet is lower should be set as the delay time. In this regard, despite the fact that the delay time in a high ambient temperature can be short as compared to a delay time in a lower ambient temperature, the starter system in a state of the high ambient temperature should be controlled based on a delay time in the lower ambient temperature. Accordingly, it is difficult to improve the startup performance of the engine.
Accordingly, in the startup control using the idling stop function, it is preferable that the startup control is realized by the software control in which the delay time is set according to the detected ambient temperature of the coil or the electromagnet to improve the startup performance of the engine in the high ambient temperature and to assure the startup of the engine in the low ambient temperature while preventing occurrence of the abnormal noise.
In this way, it is considered that the engine is started up based on the hardware control when the startup of the engine is controlled by operating the starter switch to turn on the starting switch, and the engine is started up based on the hardware control when the startup of the engine is controlled by the idling stop function.